1. Field of the Invention
The invention has to do with the perforation of film material generally, but not exclusively, of thermo plastic material. Heated perforation pins are carried by a rotating cylinder and the film to be perforated is forced against the pins by a pressure means such as a deformable roller. The heated pins cause perforations in the film and partially melt the film so that uniform tear resistant perforations are formed.
2. Discription of the Prior Art
Heated pin perforators have been provided wherein the pins are heated from a heat source inside the pin hosting rotating cylinder and wherein the pins are heated from a heat source on the exterior of the pin hosting rotating cylinder as well as a combination of both.
Perforation of thermo plastic film materials is very desirable for many applications where a wrapping having permeability is desirable. Typical applications include the wrapping of food articles such as vegetables where conventional wrapping products prevent the free flow of air to the product thereby causing the product to spoil. Perforated films also find applications as filtering medium.
However, none of the prior art heated pin perforation machines have the advantage of having an internally heated pin hosting rotating cylinder with a first external heat source adjacent to and longitudially disposed along the length of the cylinder but also providing a second focused heat source adjacent to and longitudially disposed along the length of the cylinder.
Furthermore, no prior art devices are known to the applicant hereof wherein the external heat source adjacent to the cylinder is pivotally mounted for movement from a position proximate the cylinder to a position providing access to the cylinder.